Apparatus for clearing wells



June 3, 1941- l. LooMAN APPARATUS FOR CLEARING WELLS Original Filed Dec,16, 1939 2 Sheets-Sheet 1 all vlllllfllllllllIIIIIIIIIIIIIIII1441111!!JPIJ T M @2% June 3, 1941.

I. C. LOOMAN APPARATUS FOR CLEARING WELLS Original Filed Dec. 16, 1939 2Sheets-Sheet 2 Patented June 3, 1941 2,244,253 Arrm'rvs Fon CLEARINGwsLLs Iris C. Looman Borger, Tex., assigner to Electrical TreatingCompany, Dallas, Tex.. a corpora- Ytion of Texas Original applicationDecember 16, 1939, Serial No. 309,594. Divided and this application May24, 1940, Serial No. 337,031

Claims.

'I'his invention has to do generally with the removing of congealedparafllnic and asphaltic bodies in oil wells, and relates particularlyto an improved system for electrically heating wells whereby it is madepossible to efectively remove such congealed bodies at whatever locationthey may occur in the well. This application is a division of mycopending application Ser. No. 309,594, filed December 16, 1939, on Wellclearing system.

Heretofore it has been proposed to electrically heat wells interiorly,or to so heat the production fluid within the flow pipe or tubing. bythe use of various specific forms of heating apparatus and for variousparticular purposes. In the comparatively early development of the artit was proposed to heat the fluid in the bottom of a well by anelectrically energized heater suspended on a pipe or cable, and in atleast one instance to supply electric current to the heater through asuspension means without the latter however being itself utilized as aheating element. These methods in which heating elements have been usedare impractical and inemcient because it has been necessary to confinethe heating action to a very limited space. It has not been possible toheat enough fluid so that the required temperature may be maintained asthe fluid passes through the low temperature zones considerabledistances above the heating element, where it is found that because ofthe temperature drop the substances begin to congeal. And, further, suchdevices are unsuited to my purposes in that all of the heatconcentration is within such a short space that it is impossible to heatthe fluid to maintain the desired temperatures in the normally coolerzones above, as the fluid passes upwardly through them, or to attempt todo so without over-heating the oil or causing congealed bodies to becomeso plastic as to have excessive adherence to the tubing at the hightemperatures. To attempt to supply locally al1 the heat necessary toelevate the fluid temperatures in other parts of the well, above themelting or softening point of the congealed bodies, would also involvedangerously overheating the tubing itself. Another proposal has been toheat the well fluid being discharged through the tubing by an electricalconductor run down Within and spaced from the tubing. Patent No.1,646,599, issued October 25, 1927, to Schaefer, proposes toelectrically heat a flow tubing that is thermally insulated exteriorly,for the purpose of heating the liquid within the tubing to cause theWell to flow by expansion of the fluids. While perhaps being suitable asa means of melting or removing meltable congealed bodies in the bottomof the well or within the flow tubing, such prior systems are notadaptable, and insofar as I know have never been attempted to be used,for the purpose of removing accumulations of congealed paraiilnic andasphaltic bodies from any or all the various locations where they mayoccur in a well, and from which these bodies must be removed ifsatisfactory production and operating conditions are to be maintained.

My primary object is to provide an improved and, in fact,characteristically different type of well heating system whereby it ispossible to remove congealed bodies from any location or locations inwhich they may occur within the well or flow tubing, and to so controlthe heating as to be able to limit or confine the application of heat toparticular or pre-determined portions of the well or tubing whereheating is necessary. In accordance with the invention, heat is suppliedto the well fluid by passing electrical current through a conductor runin the well and directly contacting the well fluid. This conductorordinarily and preferably comprises simply the usual flow tubing, whichis of uniform thiclmess and conductivity so that a given amount ofspecially generated or transformed electric current of high amperage andsufficient voltage may be introduced to permit a necessarypre-determined degree of heat to be maintained throughout the heatedlength of the tubing, and which is provided with'insulators to maintainthe tubing in spaced relation to the wall of the well or casing.

Provision is made for heating only a portion and variable length of thetubing from a point above its lower end, by suitable means such as aconductor or adapter carried by the tubing and engaging the wall of thewell, the position of the conductor being adjustable and variablelongitudinally of the tubing. By positioning the conductor with properrelation to the pre-determined location of the congealed bodies to bemelted in the well, the heated section of the tubing may be confined andlimited to the necessary section or depth of the well that requiresheating. This system, has the further advantage of permitting less thanthe entire length of the tubing to be heated, and therefore with a givenpotential of current, which is variably controlled, the degree of heatnecessary is confined to that section of the tubing through which thecurrent is passed and eliminates the possibility of intense or excessiveheating.

The invention is also distinguished from prior well heating systems inthat it is operable in conjunction with any known method of productionand especially a well pump carried by the tubing. As will appear later,the pump serves a purpose in addition to its usual function, ofproviding valve means for retaining pressure in the well, andalternately, it also enables production to be maintained, if desired,while the well is being heated, due to the fact that the entire lengthof the tubing above the adapter may be heated and uniform heating of thetraveling fluid maintained until the fluid is exhausted at the surface.

The advantages of the invention will perhaps be better appreciated byreferring briefly to illustrative conditions that have been encounteredin actual operations, and the manner in which the present system hasoperated to improve them. For example. the Texas Panhandle has manywells in which the formation of paralne is considered to be one of themajor production problems. In these wells the last string of casing maybe set at a point approximating 2700 feet and then the well is drilledto a total depth ranging upwards from 180 feet below the casing. Thetubing string is run to a point within say 5 feet of the bottom of thehole, and thus to a depth considerably below the casing. Fluid levelsare usually at varying points up to 1500 feet. In most cases, the bottomhole temperatures are sufficient to keep the paraillne in solution, butas the fluid is being pumped through the tubing, it passes throughlocations in the well at which the temperatures are considerably lowerthan bottom hole temperature. These colder zones may be below the usualfluid level or they may be above it. The fluid shows definite heatlosses as it is pumped through these points of low temperature, andfurther heat losses are caused by the expansion of gases carried by thefluid at elevations of reduced pressures, so that the ternperature ofthe fluid drops below that of the bottom hole temperature and paraffinebegins 'to congeal in the tubing. Also it is often found that the fluidlevel in the well may extend up into the cooler zones so that the uidtoward the top may be considerably lower in temperature than that at thebottom of the hole. In such cases, when the well is started pumping andthe fluid level is lowered, parafline will collect on the outside of thetubing from the fluid level down to that point at which the fluid againbecomes warm enough to keep the parafllne in solution. Under suchconditions it is necessary to be able to place the conductor at anypoint either above or below the fluid level, and either within thecasing string, or below it, in order to meet all the requirements.

It is also found that when some wells are pumped from time to time andtheir normal fluid levels are depressed, the expansion of gasesliberated and escaping from the formation will lower the temperature ofthe remaining fluid in the well and cause a settling out of parafline inthe formation. By properly setting the conductor above the bottom of thetubing string it is possible to heat the remaining fluids in the hole toa temperature sufficient to re-dissolve the congealed material, andthereby clean the surface of the formation and allow the paraffine to beremoved from the well bore by the method of production being used.

The present system may be used to advantage not only for the removal ofparafline but also for purposes of restoring production in wells thathave ceased t0 flow. In many instances parafline congeals in the tubingto the extent that it has been necessary to run a parailine knife or touse chemicals. Frequently the bottom hole gas pressure is overcome bythe hydrostatic pressure of an accumulated column of fluid so that thewell ceases to flow and it is necessary to use a swab or compressor, orsome other artificial means for causing the well to flow until itbecomes live enough to produce of its own accord. These usual artificialmethods require considerable time,

special equipment, and are at best expensive. By installing theconductor of my system some distance below the top of the fluid leveland providing a standing valve in the tubing string to permit upwardflow of the fluid and gas but prevent downward flow, and then by heatingthe tubing and thereby generating gas from the fluid in the well, theexpansion of the confined gases between the casing and tubing caused bythe heat creates a downward pressure on the well liquid, giving somewhatthe same effect as a compressor or swab, sufficient to cause the well toflow. At the same time I eliminate the accumulated paraifine much morecheaply and efficiently than by the usual chemical, or parailine knifeprocedure.

In some Oklahoma and other flelds a very bad parailine condition isexperienced both inside and outside the tubing. The outside accumulationof parailine is caused by the lowering of the fluid in the hole, andcooling as a result of the expansion of gas liberated from the fluid.The accumulation of parafllne between the casing and tubing is in manycases so great that it becomes necessary to remove the tubing from thehole and spend weeks and even months with cable tools cleaning orremoving the paraffine from the casing. By placing the adapter well inthe bottom of the hole at proper depth it is easily possible to heat thetubing sufficiently to raise the temperature of the fluid in the hole toredissolve the congealed parailine and permit it to be pumped, flowed,or removed from the hole by any suitable method. Ordinarily, it isunnecessary at any time to heat the tubing string above F. in order toaccomplish the desired result. This amount of heat is in no waydetrimental to the tubing or to the fluids, but is sufcient to cause anenormous generation of gas.

All the above mentioned features and objects of the invention, as wellas the details of a typical and illustrative embodiment thereof, will beunderstood to better advantage from the description to follow.Throughout the description reference is had to the accompanying drawingsin which:

Fig. 1 is a vertical section showing the upper portion of a cased wellcontaining the flow pipe equipped with insulators and connected with asource of electrical current;

Fig. 2 is a lower continuation of Fig. 1 showing the bottom portion ofthe tubing string and the adapter or conductor;

Fig. 3 is a view similar to Fig. 2 showing the tubing and adapterlowered in open hole below the casing;

Fig. 4 is an enlarged cross section on line 4-4 of Fig. 1; and

Fig. 5 is an enlarged cross section on line 5-5 of Fig. 2.

Referring flrst to Figs. 1 and 2 of the drawings, the well bore I0 isshown to contain the usual casing Il carrying at its lower end a screenor perforated liner I2. The upper end of the casing carries the usualhead I3 which may have any suitable number and arrangement of fluidconnections shown typically as the valved lines I4 and I5. Loweredwithin the casing is the usual tubing string I6 which may be supportedon the casing head I3 by any of the usual forms of tubing hangers, asfor example the conventionally illustrated type comprising a flange I1receiving the tubing coupling I8 and resting on an annulus I9 ofsuitable electrical insulating material within the upper end I3a of thecasing head. The tubing I6 carries at its lower end the usual well pumpgenerally indicated at and shown typically to comprise a barrel 2iconnected to the tubing by coupling 22 and having at its lower end a.strainer 23 below the ball check foot valve denoted generally at 24. Thepump barrel 2l contains the ordinary tubular plunger 25 carrying thedownwardly seating ball check valve 26,' the plunger being operated bythe usual rods 21 extended upwardly through the tubing to the groundsurface.

Any suitable means may be employed to maintain the tubing IO in spacedand electrically insulated relation to the wall of the casing Il or thewall 28 o! the well bore where the tubing extends down infopen hole asshown in Fig. 3. As typical means for so spacing and electricallyinsulating the tubing, the latter is shown to carry longitudinallyspaced 'insulators 29 each comprising a sleeve 30 of rubber or othersuitable insulating material placed about and receiving within itsinterior recess 3l the tubing coupling 32. The ends of the insulatorsleeve may be beveled as at 33 to facilitate movement pastirregularities in the well, and the sleeve is provided with suitableopenings such as continuously extending, circularly spaced passages 34to permit upward flow and escape of gases past the insulators within thespace 35 between the tubing and casing or well bore.

Electrical current is supplied to the tubing I6 from any suitablesource, such as a variably controlled motor generator unit or speciallybuilt and varlably controlled transformer conventionally illustrated at36 and connected by lead wire 31 with the tubing above the casing headI3, as illustrated. The opposite pole of the generator may be connectedwith the casing Il through the lead wire shown at 38. The verticalextent of the electrical circuit through the tubing, and therefore thelength of tubing heated by the current is determined by the location ofan adapter or electrical connection generally indicated at 39, carriedby the tubing and engageable with the casing or well bore, dependingupon the location of the adapter. Again, any suitable means orattachment may be employed for maintaining an adjustably variableelectrical connection between the tubing and the wall of the well. Astypical, the adapter 39 is shown to comprise a plurality of ing theirupper ends 40a seated and secured within recesses ll of coupling 32a,the lower ends lilb of the springs similarly being secured to a sleeve42 that is slidable longitudinally on the tubing to accommodate varyingexpansion and contraction of the springs as they pass through difl'erentdiameter portions of the well bore. Springs Il frictionally engage thewall of the well to maintain an electrical connection from the tubingand thereby limit the upper length of the tubing being heated, inaccordance with the location oi.' the adapter.

In considering the operation of the system, it will be understood thatin any given instance the adapter lll will be applied to a particulartubing coupling and location longitudinally of the tubing, dependingupon the portion or depth of the well that requires heating.Accordingly, the adapter may be located at any position on the tubingintermediate its upperand lower` end and with reference to the wellitself, it may be positioned at substantially the liquid level in thewell, or any desired distance above or below that level, all dependingupon the location of the congealed paraillnlc or asphaltic bodies in thebowed springs 40 havwellat the outside of the tubing, as explained inthe introductory discussion. It may be mentioned that in the majority ofinstances the adapter will be positioned a substantial distance abovethe lower end of the tubing or pump.

As previously observed, the heated length of the tubing may be confinedto within the well casing Ii, for example the uppersection of the tubingshown above the adapter in Figs. 1 and 2, or the heated length of tubingmay extend any desired distance within the unlined well bore 2B belowthe casing, as illustrated in Fig. 3. In either instance, passage ofcurrent through the tubing above the adapter heats that section oftubing and produces a direct transference of heat from the tube to thesurrounding well uid, suflicient to raise the temperature of the uidsboth inside .and outside the tubing to melt the congealedbodies and thuseiIect their removal from the zones being heated. It is to be understoodthat in referring to the normally congealed bodies becoming melted byheat from the tubing, it is taken into consideration that conversion ofsuch bodies to a plastic or fluid state may be aided by the solventproperties of the well fluids at higher temperatures. Where the tubingand adapter are run in the unlined hole with the formation engaged bythe adapter being used to complete the circuit as in Fig. 3, the heatingmay serve not only to move congealed bodies in the well, but also tofree the formation of clogging bodies and thereby increase production.

It will be understood .that the described heat.- ing operations may becarried on either while the well is being pumped, or when pumping hasstopped, at any suitable interval and for lengths of time required for aIparticular job. Ordinarily, however, during the heating process pumpingis stopped and flow connections from .the casing head I3 are closed sothat the gas contained between the tubing and casing will remainquiescent and thereby serve as an effective insulation medium againstheat losses by convection,

I have previously referred to the fact that heating of the well fluidsin accordance with the present system may be employed to developpressure within space 35 between the tubing 'and casing to facilitatedownward displacement 'of the melted bodies to higher temperature zonesand thence to the lower end of the tubing or pump for removal from thewell in the production stream. Capacity for such pressure development isinherent in the system for the reason that check valve 2l serves tosupport within the tubing a column of fluid that may extend any distanceup to the ground surface, and above the level of liquid standing in thewell, the liquid column in the tubing thus providing, in effect, ahydrostatic back pressure which must be overcome by the pressure in thewell before further flow into the tubing will occur.

It is important that the source of current supply have certain powercharacteristics for proper and most efficient heating of the tubing, andto enable the degree of heating to be maintained under control to bestsuit conditions existing in any given instance. Ordinary well tubing,not being of high resisting material, requires current of high amperageand low voltage in order that the necessary heat may be produced thereinand the current, and therefore the resultant heating, be properlycontrolled. I! a current with the voltage and amperage in the .usualproportions were attempted to be used to produce the required heat inthe tubing, it would be necessary to runthe voltage so high against thefixed resistancev in order to gain the required amperage, that rthevoltage could not be controlled or properly insulated within the tubingstring. In the small spaces between the tubing and casing, high voltageswould arc across and the eii'ect would be uncontrollable. To obtaincurrent of desirable high amperage and low voltage, I use a variablycontrolled generating unit or transformer, of which the designation at36 may be taken as illustrative, capable of supplying relatively highamperage and low voltage current within the ranges required for alloperating conditions. To illustrate, with the adapter set at 1500 feeton 2 inch tubing, the tubing may be heated to around 120 F. by using acurrent of 50 volts and 750 amperes, or 37,500 watts, for a period of 35to 40 minutes. As will be understood, where a source of alternatingcurrent is available, a properly wound transformer may be used, insteadof a generator unit, to supply current at relatively high amperage andlow voltage, as indicated.

It will be understood that the drawings are to be regarded merely astypical and illustrative, and that various changes and modications maybe made without departure from the invention in its intended spirit andscope.

I claim:

1. In combination with a well casing formed of conductive material and apipe line formed of conductive material passing through the casingand-spaced therefrom, said line including a plurality of sections andcoupling members connecting the sections together, spacer memberscarried by the pipe line and contacting interior parts of the casing,each spacer member having an internal groove of annular form receiving acoupling member and each spacer member having its intermediate part ofcylindrical shape in cross section to contact the casing with its endportions of substantially conical shape and each spacer member havingvertical holes therein for the passage of fluid between the casing andthe pipe line, a seat forming part at the upper end of the casing, amember of non-conducting material engaging the seat forming part, ashoulder forming part on the pipe line resting on the member ofnon-conducting material and sprin-g members movably connected with alower part of the pipe line for contacting an interior part of thecasing or a part of the well below the casing for electricallyconnecting the pipe line to the casing, means for connecting the upperpart of the pipe line to a source of electrical supply and a returnconductor connecting said source to the upper part of the casing.

2. In a well clearing apparatus of the character described, thecombination comprising a production flow tubing lowered within the wellin spaced relation to the wall thereof and in diect and open exposure tosurrounding Well uid, conductor means deep in the well and substantiallyabove the lower end of the tubing electrically connecting the tubing andthe wall of the well, means for supplying to a length of the tubingextending continuously 'upward from said conductor means tosubstantially the top of the tubing electric current of suincientamperage to heat said length of the tubing to a temperature suilicientto melt congealed uid contacting the heated tubing, said conductor meansserving, to determine the vertical extent of the tubing heated to saidmelting temperature.

3. In a well clearing apparatus of the character described, thecombination comprising a production flow tubing lowered within the wellin spaced relation to the wall thereof and in direct and open exposureto surrounding well lluid, a pump at the lower end of said tubingadapted to force liquid upwardly through the tubing and to maintaintherein a column of liquid extending above the wall liquid level,conductor means located deep in the well at an intermediate portion ofthe tubing a substantial distance above said pump and electricallyconnecting the tubing and the wall of the well, means for supplying to alength of the tubing extending continuously upward from said conductormeans to substantially the top of. the tubing electric current ofsuflicient amperage to heat said length of the tubing and well iluidcontacting said length, to a temperature suflicient to melt congealedbodies, said conductor means serving to determine the vertical extent ofthe tubing heated to said melting temperature and to coniine the currentto a length spaced substantially above said pump.

4. In a Well clearing apparatus of the character described, thecombination comprising a production ilow tubing lowered within the wellin spaced relation to the wall thereof and in direct and open exposureto surrounding well lluid, conductor means located deep in the well atan intermediate portion ofk the tubing and electrically connecting thetubing and the wall of the well, said conductor means being adapted tobe positioned at different depths in the well and being connected to atubing coupling, means for supplying to a length of the tubing extendingcontinuously upward from said conductor means to substantially the topof the tubing electric current of suiilcient amperage to heat saidlength of the tubing to a temperature suiiicient to melt congealedbodies in fluid contacting said heated length, said conductor meansserving to determine the vertical extent of the tubing heated to saidmelting temperature and to confine the current to a length spacedsubstantially above the lower end of the tubing.

5. In a well clearing apparatus of the character described, thecombination comprising a production iiow tubing lowered within the wellin spaced relation to the wall thereof and in direct and open exposureto surrounding well fluid, conductor means deep in the well at anintermediate portion of the tubing electrically connecting the tubingand the wall of the well, insulators positioned on said tubing abovesaid conductor means and applied to and containing tubing couplings,means for supplying to a length of the tubing extending continuouslyupward from said conductor means to substantially the top of the tubingelectric current of suilicient amperage to heat said length of thetubing to a temperature sufficient to melt congealed bodies in lluidcontacting said heated length, said conductor means serving to determinethe vertical extent of the tubing heated to said melting temperature.

IRIS C. LOOMAN.

